swift

a1cf6d34 - [swift_build_support] Add support for building benchmarks on linux-x86_64.

[swift_build_support] Add support for building benchmarks on linux-x86_64. I put in a small little kludge to add support for this. The better solution is to refactor the supports_benchmark property from Platform to Target. We already have a similar abstraction problem with armv7 target on Darwin, where we explicitly turn off benchmarking. *NOTE* Building the benchmarks for linux still requires more cmake work. I am making some changes in a subsequent commit series to do this. If you try to compile the benchmarks, you will hit an error where ninja says that it doesn't know about the swift-benchmark-linux-x86_64 target.